Underground gasification of carbonaceous material-bearing substances



June 13, 1933. c, R c 1,913,395

"UNDERGROUND GASIFICATION 0F CARBONACEOUS MATERIAL BEARING SUBSTANCES Original Filed Nov. 14, 1929 2 Sheets-Sheet l Jmntoc June 13, 1933. 1.. CIPKARRICK UNDERGROUND GASIFICATION OF UARBONACEOUS MATERIAL BEARING SUBSTANCES Original Filed Nov. 14, 1929 2 Sheets-Sheet 2 Patented June 1 3, 1933 UNITED STATES PATENT OFFICE? LEWIS c. xamucx, or zmw xonxpu. Y.

UNDERGROUND GABII'ICATION OI CABBONAUEOUS MATERIAL-BEARING SUBSTANCES Original applicationflled November 14, 1029, Serial No. 407,024. Divided and this application fled June The present invention relates to the underground treatment of carbonaceous materials such as coals of different grades or rank,

cannel coals, oil shales, carbonaceous shales, and oil-bearing rocks. The invention has for its purpose the production of oils from the above-mentioned carbonaceous materials by regulated destructive distillation and the subsequent gasification of the devolatilized car- 10 bonaceous residues formed.

The process is particularly useful in treating carbonaceous deposits which are not profitable to mine, such as coals of high ash content or possibly containing excessive amounts of shale and slate or coals of poor weathering properties. Also the process may be applied to the residual coal in abandoned mine workings. The presence of ashforming ingredients, either as inherent mineral matter 7 or as rock inclusions, does not interfere with the effectual carr ing out of the process steps, namely, distillatlon and gasification, and as will be later described, such non-conbustible material is utilized to assist the desired reactions. By the simple operating technique described, my process produces good quality oils, also produces gas or water gas of variable composition, either of which gases may be enriched in part, orthe total quantity,

so by admixture with the rich low-temperature gas from the distillation step.

a The gasification of the carbon residue, or coke produced from the distillation step, is carried out with practically no loss of the sensible heat of the gas. I apply the step which I have described in a previous patent application Serial No. 711,554 of directing the hot gases as formed immediately into heat exchangers such as waste heat boilers for the production of steam for power or other uses. I also use the residual heat of the rock strata to preheat one or more of the reacting fluids. The process therefore is entitled to credits which may be obtained. because of the inexpensive steam available for power generation, marketable tar-oils, rich and lean fuel gases suited to domestic or industrial uses, also savings obtainable-by virtueof the low cost of the fuel used. These items should serve to make much more profitable the installafuel resources.

the coke though the yield of the gas and tar- Serial No. 462,088.

tion of large power and gas generating stations in the coal fields. The method therefore provides novel means for the more eflicient use and conservation of the countys In carrying out my invention I provide entries in way of shafts and working tunnels in the area to be treated, most of the tunnels being driven in the strata of carbonaceous materials so as to reduce as far as possible the development expense. The broken material produced in the development work will be marketed if of suitable form, but in general it will be transferred into the worked out areas or chambers to be substantially distilled 66 and gasified. v

I prefer in general to-withdra-w the lean gases produced from the coke throu h tunnels or shafts, which may be lined i necessary to prevent leakage, instead of using 70 metallic pipes or conduits laid within the working tunnels. At the entries the gases and vapors will be handled by well-known gas plant method for transferring, condensing, purifying, storage, compression and transportation. I provide in some cases for withdrawing the vapors and enriched gases by separate conduits or pipes (not shown) I laid in the working tunn ls.

Ihave found that coal, oilshales and like carbonaceous materials may be caused to yield variable quantities and types of gaseous and liquid hydrocarbons when distilled at different rates and temperatures within the range commonly referred to as low-temperature distillation. This I have described in Bureau of Mines Bulletin 249, also in my previous patent applications Serial Nos. 711,554 and 235,790. Also the carbon residue or coke formed may vary its chemical reactivity or rate at which it will gasify in contact with oxidizing gases such as air, carbon dioxide, and steam. In general very slow distillation was found to produce the richest fuel gases, the best quality tar-oils, and the most reacoils was somewhat less than by more rapid distillation.

I apply these principles in carrying out my process of distilling the carbonaceous mama be in the form of narrow tunnels, voids or fissures produced by-breaking the material sufficiently to form loose rvious masses" of uniform permeability. he proposed methods of preparing the coal to receive the heat is later described.

Some coals are quite fusible and might melt down and seal the gas'channels and thereby retard the distillation, if provisions were not made to obviate this danger. To do' so this, I apply the principles which I have worked out and described in other patent applications Serial Nos. 241,286 and 287,815. I have found that all bituminous coals pass through a state of either insi ient fusion or a very soft state and with di erent coals the range of temperature varies within which the coals remain fused. Also I have found that lumps of some coals will be softened throughout under what has been proved to be a de- 7 sirable rate of distillation and, consequently,

will agglomerate and shut oif the gas flow. However, by using larger lumps, I find that the lumps of such coals can be caused to form an outer shell or surface of rigid coke before the entire lump has softened and thus prevent sealing of the gas channels. To secure this result, I vary the temperature and oxidizing character of the heating gases, using in some cases' producer gas mixed with several times its volume of air. I am also able by this admixture to prevent the fusing of the ash or minerals present.

' The size of the lumps and the amount of fines in the broken coal can be controlled to a suflicient degree by the proper use of powder charges placed at measured positions in the coal strata which is being prepared for distillation treatment. In order to insure thorough gas contact with the coal at the base of the broken mass which may contain considerable fines, I also place'powder shots in the rock strata forming the floor of the treating area the explosion of which turns up slabs or chunks of rock which provide openings under, into and through the broken coal masses.

The time required to distill coal or other like materials and .obtain the best improvement in both the yield and quality of the liquid hydrocarbon products from oil shales and coals, has been shown in my studies to be les than seven hours for lump material, although pulverized material will yield viscous primary. products by heating for only a few seconds. It is also necessary to prevent the are 'prevente mary va large lumps of coal or like materials under-.

going distillation without the overheating and gasification of a material part of the prirs. This result is somewhat characterize by. the conditions applied in the method of shale oil productionused in Scotland in which small lumps require 8 to 12 -hours,'but diifers-in'my case by the greater amount of time reguired by virtue of the much larger lumps 0 material treated. Some of the'lumps' may be 12 to 36 inches in minimum diameter and these will uire 24 to hours to distill depending on t e amount of checking or disintegration that occurs during the treatment.

In another case I may prefer to so distill the coal as to produce high temperature tar products or their approximate equivalent and in such case higher temperatures will be applied with non-oxidizing or only slightly oxidizing gases. If, however, the type of deposit being treated offers little or no commerical inducement for attempting the production of low-temperature distillation roducts, then I will supply high oxidizing eats such as are used in the generation of producer gas or water gas but modified, if desirable, in oxygen content by admixture of recycledfuel gases soas to prevent excessive fusion or slagging of the organic or mineral substances present.

.My process also embodies the secondary treatment of vapors resulting from the lowtemperature distillation of the coals or oil shales so as to cause the production of fighter liquid hydrocarbons. This is accomplished by combining or mixing the hydrocarbon vapor stream with a stream of highly heated water gas or producer gas which are formed by permitting steam to contact with and react upon the highly heated carbonaceous materials or by permitting air, which may contain combustible gas, toact on the carbonaceous materials being treated. It is obvious that the hydrocarbon vapors issuing from the carbonaceous materials which are distilled by highly heated water gas or producer gas, will be reacted upon by admixture with the heating gases to some extent but this does not accomplish the same result as by the mixing of the primary uncracked vapors with highly heated water gas or producer gas. This is largely due to the fact that when coal is heated either by the water gas or the producer gas which are hot enough to act-upon the vapors after they issue from the coal lumps, will have already heated the surface layers of the coal lum s to such a high temperature that a type catalyzed thermal decomposition or cracking of the va ors will already have occurred in contact with or. as they pass through the pores of the solid carbon. It is this type of undesirable decomposition that I avoid in first removin the high temperatures to e ect the secondary decompositlon. One disadvantage of my vapor phase method of forming lighter tar-oils or shale oils is that the free carbon released by the treatment will be partly recipitated in the condensedoils instead 0 remainin in V the pores of the lump materials from w 'ch the vapors were originally evolved. Where the term coal is used, it is to be understood that any solid carbonaceous material-bearing substance is the implied meaning of the term. Like numbers refer to like parts in the several figures.

I have found that the chemically reactive coke residue formed by the distilling steps of my process will react with steam with considerably more rapidity and at lower temperatures than willhigh temperature cokes, and will form water gas containing a large percentage of carbon dioxide particularly if the temperature is low and there is a large surplus of steam present. -I therefore include as an alternative method in my process the consumption of the active coke residue in chambers underground'to form water gas containing a maximum of carbon dioxide. The carbon dioxide may be recovered by well-known methods of compression and refrigeration for marketing as dry ice or in other forms while the residual gas consisting largely of hydrogen will be a valuable commodity for fuel or chemical uses.

In order to better describe'my invention reference is made to drawings which will suggest forms in which my invention may be applied to carry. out the processes described and to obtain the desired products and heat exchange or heat utilizations.

Figures 1, 2 and 3 are vertical sections and plan views of one embodiment of my invention. a

This method of development is suited to the treatment of solid carbonaceous materials for the production of liquid hydrocarbons of the primary, re-formed, or high-temperature types accompanied by the simultaother uses.

Numeral 1 represents a stratum of;jcarbonaceous material which may be coal, o1l shale and the like, or oil-bearing rocks. 2 and 3 ,shaft or other entry extending-from the surface to a'point a' few feet below the stratum of carbonaceous material. is a lar e working tunnel driven horizontally at t e base of the shaft 4; it contains the air, gas and piping, and is' used by the operators. vapors at low temperatures and then mixing them withjeither water as or producer gas at .6.are development tunnels or shafts of relatively small diameter shown in this case as running at right angles to tunnel 5 and connecting therewith at substantially even distances apart from the" base of the shaft 4. The cross-sectional area of thesetunnels should be about to percent of the volume of the coal to be broken from the moval shafts which may be lined, connecting with the gas tunnels 6. The tunnels 6 may be flat or very steeplyesloping or shafts as will serve the process st. 8 and 9 are long drill holes in the roof, walls and floor of the tunnels 6. The proper spacing'of the holes 8 and 9 including their depth, size of powder charge, and order of firing, will readily spell the success or failure of the operations of the process, as will be explained herein. It is intended in accordance with the form illustrated in the drawings that the distillation and gasification of the developed coal will move in a direction away from the'tunnel 5 through the panels-or areas A1 to 5 and in areas- B1 to-5. Inorderto insure con- 'tinuous uniform gas flow until the reactions in A3. The slope of the drill holes, the powder charges, and the order of their firing will cause the floor rock to be lifted up in fairly large irregular slabs 10. Workmen will then return to the tunnel 6 and remove the broken;

coarse and fine rock from blasted trench and will arrange it in broken piles along the side of the trench. The large slabs 10 will then be laid over the trench resting on the piles of finer materials and leaving narrow gapsbetween them. The smaller rocks should then be gathered into ridges extending in the direction indicated by dotted lines 8 in panel A3 so as to direct the gases toward the trench. Next the holes 8 are fired in sequence beginning at the end nearest shaft 5, the holes near the floor in each course being fired first and the roof holes last. This will cause the mass of broken material to assume a somewhat stratified structure, the slabs or blocks of coal lying with their long axes sloping toward'the center of the tunnel and be no gas channel along the top of the broken material a a-inst the roof, in fact the pile can settle considerably before an open channel will begin to form and this will form first at the gas inlet end of the broken area. Be-' neath the rock slabs 10 will be a fairly permanent channel 11 for the hot gases to flow 'tillation treatment.

through and distribute themselves throughout the broken mass.

In treating different types of carbonaceous material-bearing substances I may prefer to use steeply-sloping tunnels 6 or they may be substantially vertical without departing from the principles of my invention. If the tunnel is so steeply sloping that the broken material will fall or slide to its lower end, it will be necessary to fire the courses of shots near the bottom first and those at the top last. If the tunnel 6 is substantially vertical, that is, a shaft or winze, there will be-no need .of blasting a trench in one side by drill holes 9. The gas inlet end of the sloping tunnel or shaft may be at either the lower or the upper end without altering the principles of my process.

I prefer to use a steeply sloping or vertical treating chamber 6 for working'some interstratified deposits of great thickness such as the oil shale measures of'the States of Utah, Colorado and Wyoming, in which case the working tunnel 5 and gas tunnel 6' will be above and below the rich strata to be worked and the chamber 6 within the rich strata. If the carbonaceous material is of the fusing or weak type structurally so that it will not support the weight of a high column of the mate rial I will drive the opening6 in a zigzag.

course so that the column of broken material will .bev supported throughout by arching against the projecting parts of the walls. Such working chambers 6 can then be as high as desired and effectually carry out the dis- This form is also well suited to treating oil soaked rocks. The principle of supporting the column at numerous points throughout its height is described in-my patent application Serial Number 285,426.

In the case illustrated in the drawings, I may prefer in treating some materials to use extremely long distillation galleries 6 full of broken material, say many hundrds of feet long, and of relatively small cross-section as compared with shorter galleries of wider cross-section s When I use very long narrow galleries of broken material 1' will so space them from the adjacent galleries'that the material formin the intervening wall se arating the galleries 6- will be likewise distil ed 'and largely-gasified by thereactions taking place within the galleries; this likewise apthrough the strata at proper distances apart and blasting the holes to cause cracks, fissures or ducts by which the hot gases described herein may be passed throu h while car out the heating and gasi cation reactions. Pipes carrying air, gas and steam will pass down through certain of the drill holes and the vapors and gas products will be removed from other holes. I

In shaft 4 are pipes 12, 13 and 14 carrying air, s, and steam respectively, into the treatln areas via the connections and valves similar y numbered. These valves will be marked so that the operator can readily roportion the three fluids to give the desired temperatures, gas compositions and gas volumes passing into the coal masses being treated. Gas shaft 7 is tightly connected at itstop to manifold 15 which is shown as having one unused opening 19, a horizontal explosion door at its top 17, a balanced check valve'18 to prevent any sudden rush of gases from entering branch 16. Branch 16 is shown as sensible heat of the hot gases merely to heatfeed water, or possibly to supply the steam for the mean power load and take care of peak loads by burning part of the gases, or use other fuels. In thebase of the boiler setting are placed drains 22 for removing heavy condensates of tar oils which may collect.

Another manifold 23 is shown connectedto the collar of the gas-shaft 7 which will serve panel B when ready to operate.

A gas control tunnel 24 is driven in the rock 2 above gas tunnel 6' but not intersecting gas shafts 7 Pipe connections 25 extend through the floor ofcontrol tunnel 24 and into the exit portals of tunnels 6 to enable the operator to make observations as to tempera: ture and gas quality of the gases issuing from chambers in which the distillation and gasification operations are in progress. Pyroine-' amazes til the temperature of the exit gases no lon er contains sufficient temperature to do use 111. work. Also' the heat of the circulated gases,

say from one or a group of galleries, may be used to preheat the broken material in galleries ready for treatment. In the latter case the hot ses would be carried by gas tunnel 6' into t e exit end of the freshly prepared galleries or charges of material and flow therethro'ugh in a reverse direction. This method-of. utilizing the sensible heat to preheat a fresh charge is described in my patent application Serial No. 287,815. The cooled gases will then be conducted by pipes corresponding to pipes 12, 13 or 14 into other galleries of materials where they are burned to carry on thedistillation and gasification reactions as above described. The hot circulated gases used for cooling worked-outchambers may also be conducted by pipes not shown directly while hot into new chambers of materials beingtreated and thus recover the residual heat of the chambers and adjacent rock strata.

In order to carry outvthe step of secondary vapor treatment of the condensable volatiles removed in the distillation step, I simply arrange to be carrying on the distillation inone or more galleries of materials while the adjacent galleries areundergoing the gasification step, so that the vapors issuing from the distillation step are mixed in gas tunnel 6' with the hot gases, producer gas or water-gas, from the gas-forming galleries. The time required to accomplish the secondary thermal treatment of the vapors is taken care of by proper design of the size and length of gastunnel 6 and the velocity of movement of the gases.

This application is a division of my application Ser. No. 407,024, the subject matter of the following claims having been originally presented insaid parent application.

What I claim is:

1. Process of gasifying solid carbonaceou deposits underground which comprises forming a passage communicating with a deposit, forming another passage within the deposit in communication with and extending from the first mentioned assage by removing a substantial portion of the material in the deposit,-'eflectinv abreaking down of the walls of the secomf passage to an extent where the piled ps of the material passing-reacting gaseous medium into said lumps led pass sa at suflicient temperature to react chemica lywith the carbon for efiectin formation of gas from thecarbo n in heat exc ange relation with the gaseous medium, and conducting the gases from the deposit.

2: Process of gasif ing solid carbonaceous deposits undergroun which com rises forming a passage communicatin wit a deposit, forming another passage within the deposit passage is substantially filled with loosely in communicationwith and extending from the first mentioned pasage by removing a substantial posit, effecting a breaking down of the walls ortion of the material in the deof the second passage to an extent where the passage is substantially filled with loosely piled lumps of the material passing reacting gaseous medium into said lumps lled passage at suflicient temperatureto react chemically with the carbon for effecting formation of gas from the carbon in heat exchange relation with the gaseous medium, conducting the gases from the deposit, and abstracting part of the contained heat of the gases.

3. The method of obtaining fuel Values from underground deposits of carbonaceous material which comprises forming a passage within the deposit of a size sufiicient to ac commodate workmen, drilling holes in the walls of the passage, charging the drill holes with explosives and efiectin a breaking down of the walls of the passageliy a discharge of the explosives with the resultant filling of the passage with loosely iled lumps of the carbonaceous material 0 a size, generally predetermined by the formation of the drill holes J and the amount of explosive employed, passing aheating medium'throu h the loosely piled lumps at a temperature su icientto gasify the carbon within the material, and direct-ing the passage of the gases to the surface.

4. The method of obtaining fuel 'values from underground deposits of carbonaceous 1 material which comprises forming a working passage within the deposit, forming retort passages within the deposit communicating with and extending from said first mentioned passage, drilling holes in the walls of the retort passages, charging the drill holes with explosives and effecting a breaking down of the walls of the passages by a discharge --of the explosives with the resultant filling. of the passages with loosely piled lumps of the carbonaceous material of a size generally predetermined by the formation of the drill holes and the amount of explosives employed, passing a heating medium throu h the loosely piled lumps at a temperature su cient to gas ify the carbon within the material, and directing the passage of the gases to the surface.

5. The method of obtaining fuel values from underground deposits of carbonaceous material which comprises forming a working passage within the deposit, forming retort passages within the deposit in communica- 1 opening to permit the introduction of a heatmg medium from the working passage into the retort passages, passing a heating medium into the retort passages and through the loosely piled lumps at a temperature suflicient to gasify the carbon within the material and directing the passage of the gases to the surtace.

6. Process of treating solid carbonaceous deposits underground which comprises forming a passage communicating with a, deposit,

forming another passage within the deposit in communication with and extending from the first mentioned passage by removing a substantial portion of the material in the deposit, effecting a breaking down of the walls of the second passage to an extent where the passage is substantially filled with loosely piled lumps of the materialfpassing gaseous medium into said lump filled passage at sufli: cient temperature to remove condensable volatile and gaseous products from the material without decomposing said products, and conducting the same from the deposit.

7. Process of treating solid carbonaceous deposits underground which comprises forming a passage communicating with a deposit, forming another passage within the deposit in communication with and extending from the first mentioned pamage' by removing a substantial portion of the material in the de- 7 posit, efiectmg a breaking down of the walls of the second assage to an extent where the ge is su ntially filled with loosely piled lumps of the material, passing gaseous medium into said lump filled passage at suflicient temperature to remove condensable volatile and gaseous products from the material without decomposing said products, conducting the same from the deposit, and abstracting part of the contained heat of the gases.

8. The method of obtaining fuel values from underground deposits of carbonaceous material which comprises forming a passage within the deposit of a size suificient to accommodate workmen, drilling holes in the walls of the passage, charging the drill holes with explosivesand efi'ecting a breaking down I of the walls of thepassage by a discharge of the explosives with theresul ant filling of the-passagewith loosely piled lumps of the carbonaceous material of a size generally predetermined by the formation of the drill holes and the amount of explosive employed, passing a heating medium through the loosely piled lumps at a temperature suflicient to remove volatile products from the material,

, and directing the passage of the gases to the surface.

' 9. The method of obtaining fuel values from underground deposits of carbonaceous material which comprises forming a working passage within the deposit, forming retort passages within the deposit communicating with andextending from said first mentioned passage, drilling holes in the walls of the retort passages, charging the drill holes with explosives and effecting a breaking down of the walls of the passages by a discharge of the explosives with the resultant filling of the passages with loosel piled lumps of the carbonaceous material 0 a size generally predetermined by theformation of the drill holes and the amount of explosive employed, passing a heating medium through the loosely piled lumps ofa temperature suificient to remove volatile products .from the material, and

directing the passage of the gases to the surface.

10. The method of obtaining fuel values from underground deposits of carbonaceous material which comprises forming a working passage within the deposit, forming retort passages within the deposit in communicationwith the first mentioned passage, drilling holes in the walls of the retort passages, charging the drill holes with explosives and eifecting a breaking down of the walls of the retort passages by a discharge of the explosives with the resultant filling ofthe passage with loosely piled lumps of the carbonaceous material of a size generally predetermined by the formation of the drill holes and the amount of explosive employed, blocking the communications between the working passage and-the retort passages except for an opening to permit the introduction of a heating medium from the working passage into the retort pasages, passing a heating medium into the retort passages and through the,-

loosely piled lumps at such temperature sufficient to remove volatiles from the material, and the passage of the gases tothe surface.

' 11. Process of treating solid carbonaceous deposits underground which comprises forniing a passage communicating with a deposit, forming another passage within the deposit in communication with and extending from the first mentioned passage by removing a substantial portion of the material in the deposit, efiecting a breaking down of the walls of the second passage to an extent where the passage is substantially filled with loosely piled lumps of the material, pass ing hot fuel gases in contact with the material at such temperature as to remove condensable volatile products therefrom without consuming the carbon therein, and passing further gases of an oxidizing nature through the enlarged passage to attack the residue and produce fuel gases therefrom.

12. Process of treating solid carbonaceous deposits underground which comprises forming a passage communicating With a deposit, forming another passage Within the deposit in communication With the first mentioned passage by removing a substantial portion of the material in the deposit, effecting a breaking down of the Walls of the second passage to an extent Where the-passage is substantially filled with loosely piled lumps of the material, passing gaseous medium into said lump filled passage at sufficient temperature to remove condensable Volatile and gaseous products from the material, and conducting the same from the deposit, said passage formed in the deposit being substantially vertically arranged therein and being of zig-zag formation.

In testlrnony whereof I aflix my slgnature.

LEl/VIS C. KARRICK. 

